Not able to Upgrade to macOS Big Sur due to space issue

See used and available storage space on your Mac

• Other: Contains files that don’t fall into the categories listed here. This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.

The other option - not the best though - is perform a wipe and clean install of Big Sur.

But, regardless - there after - the issue of Empty Space will reappear. For good practices - one should alway keep 15% of the total drive capacity as Free Space.

Very Much agree with @ James Brickley on selling tiny SSD in Apple Computers.

Boy, this really irks me that Apple has been shipping Macs with only 120GB of storage. This has been a problem for years. We even ran into it at work where they procure the cheapest enterprise PC laptops and we had to start swapping drives from 120GB to 256GB because 120GB wasn't nearly enough storage for the OS and business applications. So it's not just Apple whose operating system takes a lot more storage, it's Windows 10 as well.

In the simplest of terms, the “Other” category is a combination of files that are not recognized as one of the other file types.

• Common documents and file types, including PDF, doc, PSD, etc.
• Any type of archives and disk images, including zips, dmg, iso, tar, etc.
• Files in the system folders of macOS, including temporary files, swap, voices, etc.
• Application Support files, iCloud files, Screensavers, etc.
• Cache items, including browser cache and locally stored message media files.
• Fonts, app accessories, application plugins, and app extensions.
• Various file and file types not recognized by Spotlight, for example, a virtual machine hard drive, Windows Boot Camp partitions, etc.

That means it can be a real pain to try to figure out what's taking all the space out of that 60.62 GB's of Other used space.

There's a few tools available to help such as

OmniDiskSweeper - https://www.omnigroup.com/more. (free, ancient old but still works)

Grand Perspective - http://grandperspectiv.sourceforge.net (open source, old but still works)

My Go To Tool of Choice (personal opinion)

DaisyDisk - Mac App Store

You'll need to grant these tools Full Disk Access under System Preferences -> Security & Privacy -> Privacy settings.

If you have a Time Machine drive you should connect it and let it complete a backup. One big consumer of space are the APFS file system snapshots waiting to be backed up to Time Machine. Once a backup is completed a large chuck of that Other space may clear up.

The Other category is a potpourri of files which can include:

• System temporary files

• macOS system folders

• Archives and disk images (.zip, .iso, etc. - often found in the Downloads folder)

• Personal user data

• Files from the user’s library (Application Support, iCloud files, screensavers, etc.)

• Cache files: browser, Mail

• Mail messages & attachments

• Fonts, plugins, extensions

• Safari reading list

• iTunes backups

• Crud resulting from jailbreaking your iDevice

• Game data

• Saved data files

• Call history

• Notes

• Media

• Voice memos

• Other files that are not recognized by a Spotlight search

• Media files that cannot be classified by Spotlight as a media file because they are located inside of a package

• Files created and modified by other user accounts on your Mac.

They can be located anywhere on your hard drive.

The files that you have control over are located in the Documents, Downloads, Pictures, Music and Movies folders.  You can use either of these two free apps, GrandPerspective  or OmniDiscSweeper, to find the largest files on your drive so you can determine if they can be deleted or moved to an external HD for storage.  

Note: you can empty the Downloads folder after the apps and/or updates that were downloaded have been installed or applied.  Many users have found a couple of Gigabytes of files in their Downloads folder which are no longer needed. 

You can't upgrade if you don't have enough space.

"If upgrading from macOS Sierra or later, your Mac

needs 35.5GB of available storage to upgrade. If upgrading from an

earlier release, your Mac needs up to 44.5GB of available storage. To

upgrade from OS X Mountain Lion, first upgrade to OS X El Capitan, then

upgrade to macOS Big Sur."